Softballs are comprised of two parts, including a core and a covering. The material used for covering is composed of synthetic, composite or natural leather, which is commonly dyed yellow to help with visibility. The leather is stitched around the ball with red thread made of either linen or cotton. While the covering of a softball remains consistent, its core can be comprised of a variety of materials.
Softball’s Core
The material used for the center of a softball’s core varies depending on the quality of the ball. Higher-quality softballs, like ones used for collegiate and professional play, have cores that are composed of long fiber kapok, a fiber obtained from a tropical tree in Central and South America, or polyurethane. These materials help to improve resiliency and durability of the ball, increase ball flight distance when hit, prevent bat damage and limit bat vibration and sting. In balls used for recreational and youth play, typically granulated cork, rubber, or a combination of both cork and rubber is used at the ball’s core. These materials are softer to limit injury potential in less-skilled players. No matter the material used at the core’s center, kapok, a fibrous yarn, is wound tightly around the center of the core to ensure that every ball is of the exact 12-inch size specifications.
Main materials used in a composite softball bat:
- Carbon fiber sheet -C3H3N: Form the shape of the bat
- Aramid- C₁₄H₁₀N₂O₂: Synthetic fibers that help build the walls
- Epoxy-C₂₁H₂₅CLO₅: Structural Adhesive that keeps everything in the bat together
- Poly-carbonate plug-C₁₅H₁₆O₂: Used for weight and to seal off the end
- Steel Rod/Pin-Fe₃C: Rob is used to shape the bat, but is eventually removed. Pin is used to make the correct balance
- Fiber Glass- (Al₂O₃)₉(B₂O₃)₅(MgO)₈₅(SiO₂): A part that helps build the walls
Steps to compose a composite softball bat:
-
Carbon Fiber Sheets are ironed together then cut to shape
-
Carbon Fiber Sheets are spiralled around a steel bat form and poly-carbonate tape is used to squeeze the air out between layers. Bat is then baked in an oven to fuse them all together.
-
Tape is removed. Tubes of braided carbon and fiberglass, carbon fibers, and a synthetic weave called aramid are slid on and taped, before putting the softball bat into a mold.
-
Epoxy Resin is injected, mold applies hot pressure to bake layers together, then forming the shape
-
Steel form is removed since bat can hold its own form, and is tested for flexibility using pneumatic equipment
-
The end is cut to shape a knob, and bat is sanded
-
Bat is painted with primer, spray paint, and decals and laser printers to make design
-
Poly-carbonate plug is added to the end for weight and is sealed with resin
- A steel pin is drilled into the knob to attain correct balance
Main Chemicals, Compounds, Components
Two Main Components: Carbon Fiber and Epoxy
1. Carbon Fiber:
Carbon Fiber is extremely thin strands of carbon twisted together, and these strands are exceptionally strong and remarkably light weight. Its chemical formula is C3H3N. Carbon Fiber is stronger than steel, and also lighter. It was created in 1958 by Roger Bacon at the Union Carbide Parma Technical Center in Ohio. Sheets of carbon atoms are placed into a hexagonal pattern, like graphite to form the strands. It is used in composite materials because it is so strong. This is useful for softball bats because the continuous repetition of contact with softballs will not damage it. Also, it’s characteristic of being lightweight is good for bats because it allows the batter to swing the bat faster and more powerfully.
2. Epoxy Resin:
Epoxy is a great structural adhesive made out of two parts, epoxide and polyamine. Its chemical formula is C₂₁H₂₅ClO₅. This resin is used to keep all the materials of a softball bat together. It is used on the outside to hold everything together, and on the inside to hold the layers of materials together. It is man made and was created in the U.S. in 1972. It is used where high strength bonds are needed. Other characteristics include good heat resistance, and good conductor of electricity (one reason why bats should not be used during lightning storms).